TMS320F2800137: The output voltage ripple is large during LLC soft-start.

Tool/software:

Hi Experts,

I am asking for my customer.

They designed for 1000W LLC follow up our reference design TIDA-010062 and PMP41006 software, I attached the figure below: How to solve this issue? Thanks. 

Ch1: Resonant Cavity Current

Ch2: LLC Downpipe VDS

Ch3: Output Voltage

Ch4: LLC Downpipe VGS

Copy of 1000W LLC test data for soft-start.xlsx